RFeB-based magnet and method for producing RFeB-based magnet

Abstract

Provided is a combined type RFeB-based magnet, including: a first unit magnet; a second unit magnet; and an interface material that bonds the first unit magnet and the second unit magnet, in which the first unit magnet and the second unit magnet are RFeB-based magnets containing a light rare earth element RL that is at least one element selected from the group consisting of Nd and Pr, Fe, and B, in which the interface material contains at least one compound selected from the group consisting of a carbide, a hydroxide, and an oxide of the light rare earth element RL, and in which an amount of a heavy rare earth element RH that is at least one element selected from the group consisting of Dy, Tb and Ho in the second unit magnet is more than that in the first unit magnet.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an RFeB-based magnet that contains R (rare earth element), Fe, and B, and a method for producing an RFeB-based magnet.BACKGROUND OF THE INVENTION[0002]The RFeB-based magnet was found by Sagawa et. al. in 1982, and has an advantage that many magnetic properties such as residual magnetic flux density are higher than that of permanent magnets in the related art. Accordingly, the RFeB-based magnet has been used in various products such as a drive motor of a hybrid car and an electric car, a motor for electrically-assisted bicycles, an industrial motor, a voice coil motor of a hard disk drive and the like, a high-performance speaker, a headphone, and a permanent magnet-type magnetic resonance diagnostic device.[0003]Early RFeB-based magnets have a defect that among various magnetic properties, a coercive force Hcj is relatively low. The coercive force represents a force that resists magnetization inversion when a magnetic field...

AI Technical Summary

Benefits of technology

[0015]An object of the invention is to provide an RFeB-based magnet which is capable of locally increasing a content rate of RH at a portion in which it is necessary to increase a coercive force, and which has high heat resistance.

[0020]The combined type RFeB-based magnet according to the invention can be manufactured by the above-described method, and thus it is possible to make the heavy rare earth element RH diffuse from the bonding surface to the inside of the unit magnet. According to this, the RH can be present at the grain boundary and the vicinity of the grain boundary over the entirety of the combined type RFeB-based magnet, and thus it is possible to increase the coercive force of the entirety of the magnet. Accordingly, it is possible to prevent magnetization inversion up to a high temperature in comparison to the combined type RFeB-based magnet in the related art, and thus the combined type RFeB-based magnet of the invention can be suitably used in magnets such as a magnet for a drive motor of a vehicle which is used in an environment in which a temperature is raised to a high temperature of approximately 200° C.

[0021]The combined type RFeB-based magnet according to the invention also has an effect of suppressing an occurrence of an eddy current during use when considering that all of the carbide, the hydroxide, and the oxide of the light rare earth element RL that is a material of the interface material are insulating materials.

[0025]According to the invention, it is possible to provide an RFeB-based magnet which is capable of locally increasing a content rate of RH at a portion in which it is necessary to increase a coercive force, and which has high heat resistance.

Problems solved by technology

However, Patent Document 2 only describes bonding of a plurality of RFeB-based magnets, and does not disclose a specific bonding method.

Particularly, in a drive motor of a vehicle, a temperature is raised to 200° C. or higher during use, and thus the RFeB-based magnet in which bonding is performed with the adhesive cannot be used in this motor.

In addition, in the RFeB-based magnet that is manufactured by the second method, when a temperature is raised during use, a magnetization direction may be inverted at a portion in which a high coercive force is not obtained.

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